Bar loaders for automatic lathes

ABSTRACT

A loading device comprises a pusher for feeding a bar along a guide towards a lathe spindle. The pusher comprises a first thrust part (16, 116) which is constrained to traversing means (14) along, said path. Said first part comprises a constraint element (18, 118) for coupling with a complementary constraint element (19, 119) located on a second and removable pusher part (17, 117) which constitutes the axial extension of the first part along the guides. The two elements (18, 118, 19, 119) extend axially between the first and second parts and have their transverse dimension within the transverse dimension of the guide to run therein.

BACKGROUND OF THE INVENTION

The present invention relates to a loader for insertion of bars inautomatic lathes.

There are known loaders of bars into lathes comprising a pusher pushingaxially a bar along running guides to introduce it progressively intothe lathe spindle. A problem with said loaders is the space occupied.Indeed, the length of the loader must be theoretically equal to the sumof the length of the bar to be loaded plus the length of the pusher. Thepusher must then be sufficiently long to push the bar completely intothe lathe spindle.

To seek to reduce the space occupied, in the known art there have peenproposed loaders having two pushers, one acting along the first part ofthe thrust path and one acting along the second part. In this manner thefirst pusher can be provided relatively short since it does not have toenter the spindle and the second pusher longer since it does not need tofollow the bar except when the latter is already partially inside thespindle. The need to provide two separate kinematic mechanisms formovement of the two pushers involves however construction complicationsand relatively high costs.

To reduce the costs and complications there have also been proposedloaders in which the two pushers use the same kinematic mechanism,selective constraint means permitting choice of which pusher is to bemoved each time. The complication of said systems is however high.

There have also been proposed loaders in which the longer pusherarranges itself ahead of the short pusher. The constraint means betweenthe pushers are however always outside the space occupied by the pusherand interfere with the bar guides, causing construction complications.The pusher with the extension is not assimilable as to behaviour with anindividual pusher but produces vibrations and operating defects.

The purpose of the present invention is to obviate the above mentionedshortcomings by supplying bar loaders in which the pusher is provided intwo separable parts with the two parts behaving upon connection as asingle pusher which passes without problems into the bar guides.

SUMMARY OF THE INVENTION

In view of said purpose it has been sought to provide in accordance withthe present invention a loading device comprising a pusher for feeding abar along a guide towards a lathe spindle and comprising a first thrustpart which is constrained to traversing means along said path and saidfirst part comprising a constraint element for coupling with acomplementary constraint element located on a second and removable partof the pusher which constitutes an axial extension to the first partalong the guides and characterised in that the two elements extendaxially between a first and a second part and have a transversedimension within the transverse dimension of the guide to run therein.

BRIEF DESCRIPTION OF THE DRAWINGS

To clarify the explanation of the innovative principles of the presentinvention and its advantages compared with the known art there isdescribed below with the aid of the annexed drawings a possibleembodiment thereof by way of non-limiting example applying saidprinciples. In the drawings:

FIG. 1 shows a partial schematic side view of a first bar loaderprovided in accordance with the present invention,

FIG. 2 shows an exploded perspective view of a disconnection end for thepusher of the loader of FIG. 1,

FIG. 3 shows a cross sectioned longitudinal view of the end of FIG. 2,

FIG. 4 shows a view of a second embodiment of a disconnection end indisconnected position,

FIG. 5 shows a view of the end of FIG. 4 in connected position,

FIG. 6 shows a partial schematic cross section view of a secondembodiment of a loader in accordance with the present invention,

FIG. 7 shows a lower side view of the loader of FIG. 6, and

FIG. 8 shows a top view of the loader of FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the figures FIG. 1 shows a bar loader indicated as awhole by 10. The loader comprises a guide 11 along which is made to runa bar 12 to be fed axially to a spindle of a lathe 13. A kinematicmechanism 14, e.g with powered chain, slides a cursor 15 along the guideto give the bar the feed thrust.

The pusher for moving the bar along the guides and into the lathespindle comprises a first part 16 constrained to the cursor 15 and asecond part 17 which is removable. The first part 16 comprises at itshead constraint means 18 for engagement in complementary constraintmeans 19 present on the tail of the second part 17.

As clarified below, the constraint means are provided axial to thepusher so that the first and second parts, when constrained, provide asingle long pusher passing in the bar guide. In other words, theengagement means have a transverse dimension such as to be completelycontained in the cross section of the guide so that the pusher in twoparts behaves basically as a pusher in a single piece.

As may be seen in FIG. 1 the second part of the pusher traversestransversely to the guides by means of a hoisting carriage 20 movingbetween the raised position of FIG. 1 and a lowered position to insertthe second part of the pusher into the bar guides. The movement isachieved e.g. by means of a compressed air cylinder actuator 21.

Advantageously the carriage 20 comprises the upper half of the guides11, provided e.g. with channel elements aligned in accordance with theknown art, for the entire length of the removable part of the pusher.Gripping jaws 22 block the removable part of the pusher against theupper half-guides to permit raising thereof. For example, the grippingjaws 22 can comprise square levers interconnected by a tierod 23 to beoperated by a piston 24 so as to move between the raised blockingposition shown in solid lines and the free lowered position shown inbroken lines. During operation, initially the carriage 20 is raised andknown loading means (not shown) position the bar on the guides, whichhave a part not opposite the carriage 20 which opens radially for entryof the bar.

The first part of the pusher is then traversed by the cursor 15 so as tofeed the bar on the guides towards the spindle and the cursor completesa traverse until it reaches the position shown in broken lines in FIG. 1just over the section involved by the carriage 20. The length of thetraverse can coincide e.g. with the length of bar to be fed towards thelathe to cause the tip of the bar to reach a position near the machiningtools.

After this the cursor returns to the initial position and the carriage20 lowers the part 17 of the pusher so that the part 17 connects withthe first part 16 forming therewith a long pusher lying in the guides.The gripping jaws 22 release the pusher so that the cursor can push themalong the guides to completely feed the bar into the lathe. The longpart of the pusher has at its head a gripping jaw 25 on the bar tail topermit extraction from the lathe of the bar stub remaining at the end ofmachining. Known removal means 26 grip the stub and disengage it fromthe clamp 25 to remove it from the loader so that a new bar can be fed.For feeding of the new bar the carriage rises again and disconnects themeans 18, 19 and removes the extension part 17. As clarified below, themeans 18, 19 can call for disconnection means 27.

FIGS. 2 and 3 show a first embodiment of connection means between afirst and second part of the pusher. As may be seen in FIG. 2 theconnection means comprise a seat 28 open radially to receive acomplementary engagement end 29. The seat and the engagement end definemutual striking surfaces at least in the direction of axial running toprevent said running between the first and second parts upon radialinsertion of the end in the seat. For example, the striking surfaces areprovided by a radially narrow intermediate zone 30 inserting itself in acomplementary narrow part 31 of the seat.

To provide means of preventing mutual rotation between the two parts ofthe pusher the narrow zone 31 is provided with a non-rotating crosssection, e.g. formed generally like the letter U and complementary tothe narrow zone 30 formed by two flat surfaces on two sides of thepusher. The gripping jaws 22 block the extension part 17 before raisingof the carriage to allow keeping safely the alignment of the connectionmeans upon rotation. As may be seen in FIG. 3 the end 19 comprisesinternally a cursor 32 for yielding connection which is pushed by aspring 33 axially into the seat 28 to engage in a complementary seat 34at the head of the first part of the pusher 16. The thrust of the springis sufficient to ensure keeping the connection between the parts 18 and19 to permit simultaneously quick disconnection upon withdrawing of thecarriage 20 from the guides. When the two parts are connected togetherthe pusher thus formed behaves in all ways as a single pusher and caneasily run along the guides.

FIGS. 4 and 5 show a possible variation of the connection means 18, 19.As may be seen in said FIGS. the connection means comprise indicated by18' and 19' an axial snap connection formed by a pin or tang 35projecting axially from the part 16 to insert itself in a complementaryseat 53 in the connection means 19' causing backing of a cursor 36against the effect of a spring 37. Upon backing away of the cursor 36,balls 38 fall in a groove 39 in the tang to free a ringnut 40 which runsthus thrust axially by a spring 41. The connection thus arranges itselfas in FIG. 5 with the balls held partially in the groove 39 by theringnut 40 to prevent withdrawal of the tang 35.

To withdraw the tang disconnection means 27 seize the ringnut and causeit to traverse axially to again compress the spring 41 until the ringnutis brought back to the initial position in which the balls 38 can riseagain from the groove 39 so that the spring 37 can push the tang backout of the connection seat.

In use, when the carriage 20 carries the extension in an axial positionwith the initial pusher 16 the cursor 15 is commanded to advance so thatthe pin or tang 35 connects in 19'. For disconnection the cursor 15returns to the initial position and the clamp means 27 cause the ringnutto run as described above while the cursor 36 is left free to back outof the seat 53.

In FIGS. 6, 7 and 8 is shown a loader having a variation of thetraversing mechanism of the extension or second part 17 of the loaderformed by the carriage 20. Said variation is particularly advantageousin the case of loaders of the type for multiple-spindle lathes, i.e.where there is a plurality of parallel guides rotating to movesequentially to the loading position. It is thus described for a loaderof that type. Application also to single-spindle loaders of the abovetype is apparent to those skilled in the art.

As may be seen in FIG. 6 the loader comprises a rotating support 42supporting guides 43 for the bars. The guides are e.g. formed by knownaligned channel elements which as known can open or close for insertiontherein of the bars. Upon rotation of the rotating support 42 the barsmove sequentially into a bar insertion position. The pusher extensionpositioning and removal means comprise a pair of clamps 44 supported byarms 45 pivoted at 46 to be moved by means of an operating piston 47between a retracted position shown in solid lines in FIG. 6 and anadvanced or gripping position shown in broken lines.

As shown also in FIG. 7 the clamps 44 are supported by shafts 48, 49coupled together by gears 50, 51. One of the two shafts can rotate in aclosing angle of the clamps by means of an activator 52. Upon operationof the activator the two jaws of each clamp thus rotate synchronously toclose or open.

As shown in FIG. 8 the pair of clamps 44 faces the extension 117terminating at its head with a clamp 125 and its tail by connectionmeans 119 to engage with complementary connection means 118 located atthe head of the first part of the pusher 116 constrained to the movementmeans like the part 16 of FIG. 1.

The connection means 118, 119 are provided to have a transverseextension not greater than the transverse extension of the passage inthe guides 43 and can be equal to those described above and indicated by18, 19, 18', 19'.

From the description of the embodiment of FIG. 1 it is clear thatconnection and disconnection of the extension and feeding of the bar arepossible. For example, the clamps 44 hold firmly the extension in itsorientation for connection with the means of FIG. 2.

At this point it is clear that the pre-set purposes have been achievedby supplying bar loaders having pushers which, while forming an assemblybehaving basically as a single pusher passing in the guides, can bedisconnected to limit the length of the loader in relation to the lengthof the bars and the feeding path.

Naturally the above description of an embodiment applying the innovativeprinciples of the present invention is given merely by way of exampleand therefore is not to be taken as a limitation of the patent rightclaimed here.

For example, the proportions between the two part of the pusher and thelength of the respective feed paths depend on the actual practicalexigencies.

In addition, in the embodiment of FIG. 6 the clamps can be more than twoin relation to the length of the removable extension.

What is claimed is:
 1. A loading device comprising a pusher for feedinga bar in a path axially thereof along a guide towards a lathe spindle,the pusher comprising a first pusher part,means to constrain said firstpusher part for movement axially along the path, said first pusher parthaving a first coupling element on one end thereof, a second pusher parthaving on one end thereof a second coupling element complimentary tosaid first coupling element, said second pusher part being movabletransversely of said path between a retracted position and an operativeposition in which said coupling elements releasably engage each other,whereby said second pusher part constitutes an axial extension of thefirst part along said path, and characterised in that said two couplingelements extend axially between the first and second parts and havetheir transverse dimension within the transverse dimension of the guideto run therein, and means for gripping and moving the second part of thepusher radially of said path between said retracted and operativepositions thereof, respectively.
 2. The device in accordance with claim1 characterised in that the gripping and moving means comprise means formaintaining axial orientation between said first and second parts atleast adjacent said operative position of said second part.
 3. Thedevice in accordance with claim 1 characterised in that the gripping andmoving means comprise gripping clamps disposed releasably to grip thesecond part of the pusher.
 4. The device in accordance with claim 3characterised in that said guide comprises two sets of cooperating guideelements, the clamps comprise gripping jaws positioned adjacent one sideof the second part, and operable to push said second part against oneset of said guide elements providing a longitudinal half of said guideopposite said second pusher part, and said one set of guide elementsbeing movable with the second pusher part towards said operativeposition.
 5. The device in accordance with claim 3 characterised in thatthe clamps are supported on an arm support pivoted at one end to movebetween a first and a second position along a trajectory having the formof an arc of a circle.
 6. The device in accordance with claim 3characterised in that each clamp has a pair of gripping jaws each ofwhich is supported on one of two different axles and the two axles thusprovided bearing keyed gears coupled together, and one of said axlesbeing powered for the closing rotation of the respective jaws and theother axle moving through the geared coupling in the opposite directionfor complementary closing movement of the respective jaws.
 7. The devicein accordance with claim 1 characterised in that the guide comprises aplurality of spared parallel guides rotating around a common axle tomove in sequence into a position of bar feeding therein.
 8. The devicein accordance with claim 1 characterised in that for mutual coupling oneof said two coupling elements has therein a recessed seat for releasablyretaining therein a complementary portion of the other coupling element.9. The device in accordance with claim 8 characterised in that the seatis open radially to receive from the radial direction the complementaryportion of the other coupling element, and the seat and complementaryportion defining mutual striking surfaces at least in the axial runningdirection of the pusher to prevent axial movement between the first andsecond parts upon radial insertion of the portion in the seat.
 10. Thedevice in accordance with claim 9 characterised in that saidcomplementary portion comprises an intermediate zone radially narrow toengage in a complementary narrow part of the seat.
 11. The device inaccordance with claim 10 characterised in that at least one part of theseat comprises means for preventing mutual axial rotation between thetwo parts.
 12. The device in accordance with claim 11 characterised inthat the means for preventing mutual axial rotation comprise a narrowzone of the seat having opposed, flat surfaces.
 13. The device inaccordance with claim 12 characterised in that said zone of the seat isshaped transversely like the letter U.
 14. The device in accordance withclaim 9 characterised in that in the seat has therein a spring-loadedcursor one end of which is releasably engaged in a complementary axialseat in said complementary portion.
 15. The device in accordance withclaim 8 characterised in that the recessed seat is surrounded by a ringnut and an array of locking bills, and is arranged axially to receive inan axial bore therein a complementary axial tang formed on thecomplementary portion of the other element, a spring-loaded pusher ismounted in the bore in the seat for engagement and movement to aretracted position by said other element, said ring nut being operativeupon retraction of said pusher to move said balls towards the interiorof the seat to be partially received in a peripheral groove in the tangto secure the tang in the seat, a spring urging said ring-nut to alocking position to block the balls in the position of partial receptionin the groove in said tang, and said ring nut being movable into areleasing position to effect release of the balls from said groove andto permit disconnection of the tang from the seat.
 16. The device inaccordance with claim 8 characterised in that the said one couplingelement is connected to the second, extension, part of the pusher.